Osteomyelitis in the Hospitalized Patient: Master the MRSA, MRI, and Mandatory Biopsy Rules for Hospitalists

In this episode of Hospital Medicine Unplugged, we sprint through osteomyelitis—spot early, culture smart, hit bugs hard, cut dead bone, mobilize the team.

We open with the do-firsts: risk scan (diabetes, PAD, trauma/surgery, prosthetics, IVDU, MRSA exposure), focused exam for focal bony pain, warmth, swelling, sinus tracts, and labs (ESR/CRP↑ > WBC). Get blood cultures if febrile or vertebral disease. MRI is your early, high-sensitivity imaging to map abscesses and necrotic bone. Definitive diagnosis = bone biopsy for microbiology + histopathology—avoid swabs/sinus cultures.

Epidemiology & bugs: S. aureus (MSSA/MRSA) dominates; add gram-negatives (esp. in trauma, healthcare exposure, IVDU), polymicrobial in diabetic foot, and Kingella in kids. Tailor to host, route (hematogenous vs contiguous vs direct inoculation), and local resistance.

Antimicrobials—build the targeted backbone: • Empiric (ill or vertebral): MRSA coverage (vancomycin or daptomycin) + broad gram-negative (ceftriaxone/cefepime or FQ when appropriate). Consider Pseudomonas if risk factors; anaerobes for diabetic foot. • Narrow fast when cultures/susceptibilities return: MSSA → cefazolin/oxacillin; MRSA → vanc/dapto/linezolid (watch tox); Kingella → β-lactams. • Duration typically 4–6 weeks (longer if chronic, residual infected bone, or vertebral). • IV-to-PO switch works in stable patients with source control and susceptible organisms—choose high-bioavailability, bone-penetrant agents (e.g., FQ ± rifampin for staph with hardware, clindamycin, linezolid, TMP-SMX + rifampin when appropriate). Monitor for tox and interactions (rifampin, linezolid).

Surgery & source control—when to cut: • Chronic disease, abscess, sequestrum, sinus tract, failure of medical therapy, or unstable hardware → operative debridement. • Hardware strategy: remove if loose/infected; consider DAIR (debridement, antibiotics, implant retention) if stable hardware, early infection, and good debridement. • Dead-space management with antibiotic beads/spacers; plan staged reconstruction with plastics/ortho for coverage.

Special populations you can’t miss: • Vertebral OM: ≥6 weeks targeted therapy; urgent surgery for neurologic compromise, epidural abscess with deficits, instability, or failure of antibiotics. • Diabetic foot OM: often polymicrobial—pair aggressive debridement, vascular assessment/revascularization, off-loading, and tailored antibiotics; shorter courses possible after clean-margin minor amputation. • Prosthetic-associated & fixation infections: consider rifampin-based combos for staph (if hardware retained and susceptibilities allow).

Monitoring that sticks: • Track pain, wound status, function, and ESR/CRP trends; falling CRP supports response. • Re-image only if not improving or to define complications. • Watch drug safety: vanc AUC/AKI, linezolid cytopenias/neuropathy, FQ tendinopathy/QT, rifampin interactions.

Complications—don’t blink: pathologic fracture, chronic draining sinus, epidural/psoas abscess, relapse, amputation (diabetes/PAD), sepsis. Early escalation changes trajectories.

System moves that raise your cure rate: (1) MRI early + two sets of blood cultures when indicated. (2) Hold broad-spectrum if stable until bone cultures (don’t sterilize the biopsy). (3) Pathogen-directed regimens with IV→PO plan and toxicity labs embedded. (4) Multidisciplinary board: ID + ortho + plastics + vascular + wound care + endocrinology. (5) Hardware algorithm (retain vs remove) + DAIR criteria. (6) DFO pathway: probe-to-bone, imaging, vascular workup, off-loading, staged debridements, targeted antibiotics, 6-month recurrence surveillance. (7) Discharge bundle: OPAT or oral step-down with clear stop date, lab monitoring schedule, glycemic control, smoking cessation, footwear/off-loading, and wound clinic follow-up.

Fast, culture-led, and scalpel-savvy—get the bug, get the bone, get the source, and get the team.